Preheat oven to 170°C (approximately 340°F). Rinse summer squash and cut into 1-2 cm (approximately 1/2 to 3/4 inch) cubes. Peel and finely chop onion and garlic. Drain and coarsely chop olives. Heat oil in an ovenproof pan. Add summer squash and cook briefly. Add onions and garlic and cook, stirring. Stir in olives and thyme. Whisk eggs with milk, season with salt and pepper and pour over squash mixture. Crumble feta cheese evenly over the top and sprinkle with half of the pine nuts. Place pan on the center rack of the oven and bake until eggs are set, 10-15 minutes. To serve, sprinkle with freshly ground pepper and remaining pine nuts.